This invention relates to tire measurement, and more particularly to the measurement of the diameter and bead-to-bead dimension of a tire casing in conjunction with a tire retreading operation.
In tire recapping or retreading operations, it is common to mount the tire upon a buffing machine which removes the remainder of the worn tread from the tire casing. Subsequently, new tread, or camelback, is affixed to the tire casing through the use of procedures and equipment that are well known in the art. For example, a molding process can be utilized in which the tire casing and camelback are inserted into a mold and are bonded together by vulcanization. Also employed are tread-applying machines wherein the camelback is joined to the tire casing as the casing is being power rotated.
In conjunction with such operations it is necessary to employ a matrix which carries appropriate tread configurations. The matrix is selected in accordance with the diameter and bead-to-bead dimension of the casing. An important factor in determining the quality of the finished product is the degree to which the matrix conforms to the configuration of the tire casing so as to optimize the vulcanizing pressure fit. Tires tend to vary significantly in size and shape and are subject to varying degrees of distortion from use, depending upon the manufacturer, style, model, etc. of the tire. This requires that the diameter and bead-to-bead dimension of each casing be accurately measured prior to being recapped so that the proper matrix can be selected.
In furtherance of this end numerous tire measuring machines and techniques have been proposed, as evidenced by the disclosures of U.S. Pat. Nos. 1,797,389, 2,636,277, 2,650,437, 3,007,251, 3,633,279, and 3,690,010. Prior proposed tire measuring devices may be characterized by serious shortcomings, such as providing only rough estimates of true tire size, being subject to distorted readings due to the presence of protruding sidewalls or scuff-bars, and requiring time-consuming hand measurement, or other measurement that is subject to human error. Some devices are in the form of large, immobile machines to which the tire must be brought and mounted in a special time-consuming operation. In present day facilities, which may process hundreds of tires per day, it is important that the proper matrix be determined quickly as well as accurately.
It is therefore, an object of the present invention to overcome problems of this sort.
It is another object of the present invention to provide a light-weight, easily manipulatable tire measuring instrument which can be operated rapidly to produce highly accurate measurements that minimize the chances for error.
It is a further object of the invention to provide such an instrument which is portable and which can be adapted to various tire-mounting machines.